WxUSAF

January Storm Term Threat Discussions (Day 3 - Day 7)

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31 minutes ago, BristowWx said:

My yard is in/near that jackpot zone.  Can’t complain but this still seems like it’s teetering on collapse.  Must be the Euro lack of enthusiasm.  

Comparing the most recent couple GFS runs to say 0z/6z yesterday, it seems to be taking baby steps towards the Euro at h5. Less spacing/more interaction with the NA trough, and so not as much ridging out in front. A shortwave can't induce deep low pressure at the surface when it is too close to the upper convergence region of a downstream trough.

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Comparing the most recent couple GFS runs to say 0z/6z yesterday, it seems to be taking baby steps towards the Euro at h5. Less spacing/more interaction with the NA trough, and so not as much ridging out in front. A shortwave can't induce deep low pressure at the surface when it is too close to the upper convergence region of a downstream trough.
Just so stupid how things come out of nowhere and ruin our snow

75d9855be9824cf160a5da2303f58207.gif

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6 minutes ago, CAPE said:

Comparing the most recent couple GFS runs to say 0z/6z yesterday, it seems to be taking baby steps towards the Euro at h5. Less spacing/more interaction with the NA trough, and so not as much ridging out in front. A shortwave can't induce deep low pressure at the surface when it is too close to the upper convergence region of a downstream trough.

Just be gentle when it caves

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2 minutes ago, Ji said:

Just so stupid how things come out of nowhere and ruin our snow

75d9855be9824cf160a5da2303f58207.gif

Its not coming out of nowhere you can clearly see it diving south eah run...Webb showed a graphic showing how that feature was diving in from the artic at breakneck speed. That's what is going to suppress this thing for central VA and Northern NC. I'm calling it now honestly...hopefully getting an inch or so on Thursday is my bar.

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1 minute ago, Ji said:

Just so stupid how things come out of nowhere and ruin our snow

75d9855be9824cf160a5da2303f58207.gif

Not sure that TPV lobe is the biggest problem. I am talking about what's going on out in front. Focus on the heights to the east on this animation. Less spacing/more interaction with the NA vortex.

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Just now, CAPE said:

Not sure that TPV lobe is the biggest problem. I am talking about what's going on out in front. Focus on the heights to the east on this animation. Less spacing/more interaction with the NA vortex.

Maybe it will phase

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10 minutes ago, CAPE said:

Comparing the most recent couple GFS runs to say 0z/6z yesterday, it seems to be taking baby steps towards the Euro at h5. Less spacing/more interaction with the NA trough, and so not as much ridging out in front. A shortwave can't induce deep low pressure at the surface when it is too close to the upper convergence region of a downstream trough.

I would say Para would be a great happy medium for everyone in the forum IMO specifically with distribution of snow totals if taken at face value. Manages between 00z and 06z to have strengthened the storm by a couple mb albeit It is hauling ass. Has it at 988 east of RIC. 

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7 hours ago, LP08 said:

15CE1CA2-5DC9-4F6E-AE86-74961CB68C57.png

 

7 hours ago, PivotPoint said:

Why is it that TT looks like this... WB is way better. Must be the algo it uses. Huh

image.thumb.png.7fa953889d59757544d0e3d6ef599e45.png

 

7 hours ago, Cobalt said:

GFS is not gonna get a handle on the snow maps even with Kuchera.. using a precip map shows that yeah its pretty juicy for many. 

gfs-deterministic-ma-precip_24hr_inch-1874800.thumb.png.407b97fb4ff91c9a37d9e8d485ff34f7.png

Yea, but what I was getting at was why does the snow map on the 24hr WB look different than the snow map on TT? DC on WB is completely different. So it has to use a different algorithm

See maps above yours

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57 minutes ago, CAPE said:

Not sure that TPV lobe is the biggest problem. I am talking about what's going on out in front. Focus on the heights to the east on this animation. Less spacing/more interaction with the NA vortex.

Is that vortex retrograding to the west?

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12 minutes ago, Wonderdog said:

Is that vortex retrograding to the west?

Hey Wonderdog.  Unless this totally craps the sheets we could get our first warning level snow in a billion years...give or take a billion .  

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34 minutes ago, Wonderdog said:

Is that vortex retrograding to the west?

The GFS has trended further west/more interaction with that feature over multiple runs. 

eta- To be clear, I am not saying this is going to wreck the chances of a good outcome, just that this is closer to the Euro depiction wrt this feature. 

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EPS members snow/sleet totals (inches) for the last 14 (00 and 12 UT) runs (College Park) through 00 UT Feb 3

90th percentile: 9 15 12 15 12 16 18 12 13 10 10 11 9 10

80th percentile: 6 10 11 9 10 12 13 9 11 7 6 8 6 8

70th percentile: 6 6 9 8 7 11 11 8 9 6 3 6 5 6

60th percentile: 4 5 8 6 6 7 9 7 7 4 2 5 5 5

50th percentile: 3 4 6 5 4 6 7 6 6 2 1 4 4 4

40th percentile: 2 3 4 4 4 5 6 5 6 2 0.8 4 3 3

30th percentile: 2 1 4 3 3 4 5 4 5 0.9 0.6 3 3 2

20th percentile: 0.7 0.6 3 2 2 3 3 4 3 0.5 0.4 2 2 1

10th percentile: 0.5 0.3 1 1 1 1 3 3 1 0 0.1 1 2 1

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The TPV (as represented by GFSv16) continues to accelerate south/southeast and begins (continues?) to influence our favorite anomaly.  Based on the movement of the TPV one would think we are looking at different times but no all of the plots below are from 7 AM on the 28th

743181620_trend-gfs_para-2021012318-f114.500h_anom.conus(1).gif.bdfb9dd91de19e5fc82c040ee92ec652.gif

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30 minutes ago, BristowWx said:

Hey Wonderdog.  Unless this totally craps the sheets we could get our first warning level snow in a billion years...give or take a billion .  

Can I just get clarification from you or @CAPE as to what happens if the models are mistiming this TPV and it comes even further south and east. Does that mean confluence starts to strengthen and force the storm more south of its current projection? 

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30 minutes ago, dallen7908 said:

The TPV (as represented by GFSv16) continues to accelerate south/southeast and begins (continues?) to influence our favorite anomaly.  Based on the movement of the TPV one would think we are looking at different times but no all of the plots below are from 7 AM on the 28th

743181620_trend-gfs_para-2021012318-f114.500h_anom.conus(1).gif.bdfb9dd91de19e5fc82c040ee92ec652.gif

Euro has had the same general trend with that feature. Fwiw, the CMC had the strongest/ furthest south TPV a few runs ago(almost phased), and still produced a good snowstorm. It has since shifted it further north and weaker.

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Good morning all! From Larry Cosgrove:

The forecast for the later week exemplifies what makes synoptic meteorology both exciting, while at the same time stressful. Unlike the ejecting disturbance in the near term, which will have issues with confluence and orographic dispersion, the second impulse will have an ideal chance at growth as the center will redevelop after crossing the Appalachian Mountains in southern Virginia on early Thursday morning. With a portion of the mAk vortex in Newfoundland retrogressing back into New England, a capture mechanism at 500MB will be present which will allow for both rapid deepening and leftward recurvature. As I have cautioned since last weekend, there is a chance that the normal model rightward bias will be evident with this feature. There is a chance, about 1 in 3, that snowfall impacts, along with wind, could be felt along the Interstate 95 corridor on Thursday and Friday. Yes, the center may shift far enough off of the Atlantic coastline as to minimize winter weather risks to the major cities. But I do not like the idea of writing this feature off, since you can detect a stronger intensity and more west trajectory in recent runs of the computer schemes.

 
As things stand now, the only relatively sure threat for heavy snow and mixed precipitation is across the Virginias, Washington DC, Maryland and Delaware. The no-snow line should run just above the North Carolina border, but I would not be surprised if the northern portion of the Tar Heel State gets some sleet or snow in the end phase of the low pressure passage, which looks to emerge int0o the open Atlantic Ocean very near Norfolk VA on Thursday afternoon. We should soon know on the Sunday 12z model runs if this is "one for the fish" or "the snowbirds got their wish".
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15 minutes ago, Buddy1987 said:

Can I just get clarification from you or @CAPE as to what happens if the models are mistiming this TPV and it comes even further south and east. Does that mean confluence starts to strengthen and force the storm more south of its current projection? 

There is always going to be NS energy to contend with. That is a function of having a weak SPV/-AO. With the high amplitude ridge to the west of the shortwave, the TPV lobe should not be as disruptive as it could be with a much flatter h5 look. Even with the southward trend of that feature on the GFS, it hasn't had a ton of impact to this point. I still think the 'bigger' issue is a bit too much interaction between the shortwave and the NA trough. The Euro has been persistent with that idea, and as a result the shortwave is not as sharp, and the surface low ends up weaker/further SE.

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33 minutes ago, dallen7908 said:

The TPV (as represented by GFSv16) continues to accelerate south/southeast and begins (continues?) to influence our favorite anomaly.  Based on the movement of the TPV one would think we are looking at different times but no all of the plots below are from 7 AM on the 28th

743181620_trend-gfs_para-2021012318-f114.500h_anom.conus(1).gif.bdfb9dd91de19e5fc82c040ee92ec652.gif

PNA ridge is better each run too. Wont make a diff until its offshore tho but would have been nice to get it to amplify more and go negative earlier.

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Ofc nothing happens in isolation, so it's always a combination of events that conspire to screw us out of snow. :ph34r:

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If there are going to be any notable changes with this, it will likely be in the modeling over the next 24-36 hrs as the energy associated with the system moves onshore and traverses the Rockies. With these more significant systems, history has taught us that it is this period that might cause some shifting around, but we'll see. This one looks fairly close on most guidance attm.

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3 minutes ago, Ralph Wiggum said:

If there are going to be any notable changes with this, it will likely be in the modeling over the next 24-36 hrs as the energy associated with the system moves onshore and traverses the Rockies. With these more significant systems, history has taught us that it is this period that might cause some shifting around, but we'll see. This one looks fairly close on most guidance attm.

Ralph where do you feel heaviest snow swath sets up? 

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23 minutes ago, Ralph Wiggum said:

PNA ridge is better each run too. Wont make a diff until its offshore tho but would have been nice to get it to amplify more and go negative earlier.

It looks like it is trying to go negative.

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Just now, WinterWxLuvr said:

Winchester

Winchester to Bristow.  Wherever the hell that is 

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14 minutes ago, WinterWxLuvr said:

Somebody once told me there was a 6z euro. Any truth to that?

Yes, but it only goes out to 90 hrs or something 

ETA: but you know more about the weather than I do, so that might have been a joke that went over my head!

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If the CMC holds true which is between the GFS and Euro currently, I would say Richmond to Northern Neck of Virginia are sitting in a good spot.   Especially if that low starts cranking off the coast

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16 minutes ago, WinterWxLuvr said:

Somebody once told me there was a 6z euro. Any truth to that?

6z EPS looks essentially the same as 0z. Probably a tick further SE.

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